金属改性的Pd/γ-Al_2O_3催化剂在转移加氢中的应用

Metal Modified Pd/γ-Al_2O_3 Catalyst for Tansfer Hydrogenation

研究了Cu、La、Ba、Ce和Co等多种金属氧化物对Pd/γ-Al2O3催化剂在3,5-二羟基苯甲酸转移加氢制备3,5-二氧代环己烷羧酸反应中的活性影响,发现镧的改性效果最明显.得到的Pd-LaOx/γ-Al2O3催化剂在150℃下还原,催化3,5-二羟基苯甲酸转移加氢反应的转化率和选择性分别达到了90.6%和98.2%.在150℃下PdCl2被还原为Pd,而La保持氧化态.经TPR、SEM、TEM、XPS等手段分析后认为,引入的La使Pd具有适宜的粒度,低温还原时保持氧化态的La与载体产生相互作用,并对Pd的转移加氢活性的提高有利,而高温下被还原的La则对提高Pd的活性不利.

The activity of Pd-MeO2/γ-Al2O3 in the transfer hydrogenation of 3, 5-dihydroxybenzoic acid to 3, 5-dioxocyclohexane earhoxylic acid was investigated. Copper, Lanthanum, Barium, Cerium and Cobalt were used for modifying the Pd/γ-Al2O3, and lanthanum was found the best. Obtained Pd-LaOx/γ-Al2O3 was reduced at 150℃, with which the conversion and selectivity in the transfer hydrogenation of 3, 5-dihydroxybenzoic acid was respectively up to 90.6% and 98.2%. At 150℃, the PdC12 was reduced to Pd and the La was still oxide. The typical catalyst was characterized by temp-program reduction, scanning electron microscope, transparent electron microscope, and X-ray photoelectron spectrum, the analytical results indicated that lanthanum enable palladium moderate granu- larity, and the interaction of lanthanum oxides with the carrier improved the catalytic activity of Pd, reduced lanthanum went against the activity of Pd.